Two-circuit snap-action electrical switch having a single blade spring



Dec. 27, 1966 G. LANZA 3,294,931

TWO-CIRCUIT SNAP-ACTION ELECTRICAL SWITCH HAVING A SINGLE BLADE SPRING Filed March 29, 1965 Fig. 2

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United States Patent Ofilice 3,294,931 Patented Dec. 27, 1966 3,294,931 TWO CIRCUIT SNAP ACTION ELECTRICAL SWITCH HAVING A SINGLE BLADE SPRING Guglielmo Lanza, Ivrea, Italy, assignor to lug. C. Olivetti & Co., S.p.A., Ivrea, Italy, a corporation of Italy Filed Mar. 29, 1965, Ser. No. 443,347

Claims priority, application Italy, Apr. 1, 1964,

1 Claim. (Cl. 20067) This invention relates to electric snap-action switches and, more particularly, to a switch comprising an elongated actuator mounted in an insulating support for slidable movement between a first position and a second position, a pair of arms pivoted on opposite sides of said actuator and extending substantially perpendicularly to said actuator, and a spring stretched between said arms and apt to snap said arms between a first contact position and a second contact position corresponding to said first and second positions of said actuator respectively.

In the known switches of this type said spring consists either of a pair of spring blades, said spring blades being generally undulated and parallel to each other and located along the outer sides of said two arms, or of a single coil spring extending through an elongated opening in the actuator and located in a longitudinal slot provided in each one of said arms.

Due to the above structure, said known switches offer the disadvantage of an excessive thickness. This disadvantage is particularly serious when more switches have to be assembled side by side in a same apparatus, for example in the case wherein said switches must be controlled by the keys of a keyboard or by the feeler pins of a perforated tape reader or by similar equipments.

Moreover, in said switches utilizing a coil spring the mechanical strength is inadequate, particularly at the grooves on opposite sides of the actuator, wherein said two arms are pivotally mounted.

The foregoing disadvantages are obviated by the switch according to the invention, which is of the greatest simplicity and of the smallest thickness, and which is subject to a minimum of wear. More specifically, said snap switch is characterized in that said spring consists of a single metallic blade.

These and other features of the invention will be apparent from the following description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a sectional front view of the snap-action switch according to the invention;

FIG. 2 is a horizontal sectional view taken along the line II-II in FIG. 1.

The switch comprises a support 1 (FIGS. 1 and 2), made of any suitable insulating material, having a main body 2 open on one side and a cover plate 3 (FIG. 2).

The main body 2 is provided at its center with a guideway comprising two slots 4, 5, each having a rectangular section. An elongated actuator 6, consisting, for example, of a metallic rod having a rectangular section is slidably mounted in said slots. More particularly, the actuator 6 may be caused to slide, by externally acting on the insulating button 38 at one end thereof, between a first high position (as shown in FIG. 1) and a second low position. Actuator 6 bears pivoted on opposite sides a pair of metallic contact arms 7, 8 extending substantially perpendicularly from said actuator. More particularly, actuator rod 6 is provided on its opposite sides with two U-shaped grooves 11, 12 perpendicular to the longitudinal axis of said rod. These grooves engage the two inner ends 9, of said two arms 7, 8 respec tively. Also these inner ends 9, 10 are worked with a U-shaped profile. The outer end of each arm 7, 8 carries a pair of contacts 15, 16 respectively 17, 18 soldered on their opposite sides.

Between the two arms 7, 8 is stretched a spring 19 apt to snap said arms between a first contact position and a second contact position corresponding to said first and second positions of actuator 6 respectively. This spring consists of a single metallic blade, bent so as to form at least a central loop 21 and extending through an elongated opening 20 made in said actuator rod 6 at a position remote from said pivot grooves 11 and 12.

Moreover spring 19 is bent in such a way as to form also two lateral loops 22, 23 opposed to central loop 21 and extending through openings 13, 14 respectively in said arms 7, 8 respectively. The ends 24, 25 of the spring 19 are hook shaped in order to engage small openings 26, 27 respectively in the middle portion of said contact arms.

The main body 2 of insulating support 1 bears, on the opposite sides of each arm 7, 8 and in a position substantially adjacent to the outer end thereof, a pair of fixed conductors 28, 29 and 30, 31 respectively.

The pair of fixed conductors 28, 29 is provided with a pair of electrical contacts 39, 40 respectively facing the contacts 15, 16 respectively of arm 7; similarly the pair of fixed conductors 30, 31 is provided with a pair of electrical contacts 41, 42 respectively facing contacts 17, 18 respectively.

Each one of said fixed conductors 28, 29, 30, 31 is also provided with small foldable rings 43, 44, 45, 46 respectively, in order to allow a connection to be made between said fixed conductors and corresponding electrically conducting wires 47, 48, 49 by means of a simple mechanical operation consisting in pressing an end of said wire between said small rings. Since said fixed conductors are removable from their respective seats of support 1, this operation is substantially simplified.

The structure of the snap-action switch according to invention easily allows inner permanent connections to be made to fixed contacts 28, 29, 30, 31, for example between contacts 30 and 31 by means of a conducting Wire 40, as represented in FIG. 1.

The operation of the switch will now be described.

In the first high position of actuator rod 6 (FIG. 1), arms 7, 8 have their lower contacts 15, 17 respectively abutting on the lower electrical contacts 39, 41 respectively, so that an electrical conducting path is established between fixed contacts 28 and 30 through arms 7, 8, spring 9 and also rod 6. In this first contact position spring 19 urges the two arms 7, 8 against rod 6 in the respective grooves 11, 12 in upward direction with respect to the right line joining the anchorage points 24, 25, so as to urge rod 6 against a limit stop 50 built in the slot 4. Therefore in said first contact position spring 19 keeps rod 6 in its high position inside the slots 4 and 5, while arms 7, 8 are kept in their respective down contact positions.

If rod 6 is now pushed inside the support, grooves 11, 12 together with arm ends 9, 10 respectively are displaced downward. Upon passing the dead point wherein said arm ends 9, 10 are aligned on the right line joining the anchorage points 24, 25, spring 19 acts to rapidly complete the rotational movement of arms 7, 8 until said arms 7, 8 reach, through a snap action, the contact position corresponding to the low position of actuator rod 6. In this second contact position the contacts 16, 18 of arms 7, 8 abut on electrical contacts 40, 42 respectively, so that an electrical conducting path is now established between the fixed contacts 29 and 31. In said second position spring 19 urges arms 7, 8 against actuator rod 6 in the respective grooves 11, 12 in a downward direction with respect to the right line joining the an chorage points 24, 25, so as to urge actuator rod 6 against the bottom of groove 5. Therefore in said second contact position spring 19 keeps rod 6 in its low position inside grooves 4 and 5, while arms 7, 8 are kept in their respective up contact positions.

It is obvious that, by drawing rod 6 out of support 1 towards its high position, arms 7, 8 return to their first contact position.

Moreover, it is apparent that arms 7, 8 remain substantially perpendicular to actuator rod 6 in any position during operation of the switch.

In order to prevent ends 9, 10 of arms 7, 8 from sliding along the respective grooves 11, 12, said grooves 11, 12 are not continuous, but instead they are provided with projections 51, 52 respectively (FIG. 2), which cooperate with notches 34, 35 respectively at the inner ends 9, 10 of arms 7 and 8 respectively.

The Width of the spring blade 19 may be quite small, so as to reduce the total width of the switch. Moreover, openings 13, 14 which are present in arms 7, 8 respectively in order to allow passage of spring 19, consist merely of small holes rather than of a long longitudinal slit as in the known switches, so that said arms are not substantially weakened and do not require any increase in their width.

Moreover opening 20 made in actuator rod 6 to allow passage of spring 19 is located in a position spaced from the pivoting points of said arms, so that actuator rod 6 is not further weakened, and therefore even the width and the thickness of said rod may be chosen in reduced sizes with respect to the analogous known switches.

It is apparent that the snap-action switch according to invention, besides being used as a two-stable-position switch, can be used as a single-stable-position switch it a return spring for rod 6 is provided, for example a helical spring interposed between the low end of rod 6 and the closed bottom of slot 5. Furthermore, grooves 11 and 12, rather than being positioned directly opposed to one another on opposite sides of the actuator, could be made in offset positions to provide a predetermined phase difference of the closing instants for the different electrical contacts.

From the preceding description it is clear that all parts of the switch according to invention do not require special tolerances and that their mounting is particularly easy. The switch can be constructed of materials without any specially high strength.

Various changes may be made in the above described construction and different embodiments of the invention may be made Without departing from the spirit and scope thereof.

I claim:

An electric snap-action switch comprising:

(a) an insulating support,

(b) an elongated actuator mounted in said support for slidable movement between a first and a second position, and having pivot means thereon and an opening spaced from said pivot means,

(c) a pair of arms pivoted on said pivot means and extending substantially perpendicularly from said actuator, each arm carrying first electrical contact means and having an opening substantially in its middle portion,

(d) second electrical contact means located in said support in a position substantially adjacent to said first electrical contact means for cooperation therewith,

(e) a spring connected to the free end of said arms and adapted to snap said arms between a first contact position and a second contact position corresponding to said first and second positions of said actuator, respectively, said spring consisting of a single metallic blade having a generally sinusoidal shape and passing through all said openings.

References Cited by the Examiner UNITED STATES PATENTS 5/1933 Warner. 6/1958 Roeser. 

